The Crash

Trevor suggests going to check out Serpo's chopper after the hub defence. First off, you need to get there -- now that the cinema requires you to go around the back way to get to camp (exit through the screen room's fire exit), you may want to do all your trading/storing and move out for a while. Fast-travel to the Makeshift Hospital, then re-enter the city.

Once you do, turn right from the makeshift hospital's entrance to get to the ladder. That leads to a path on the east side of Henderson town going to the old fort (Fort of Henderson) where Serpo is.

The gate to the old fort is now open (you can visit it before). Kill the zombies and check the wreck. Follow the blood trail into the fort (new map).

Inside the fort's basement, navigate through the maze of dead ends to the end of the blood trail to the injured pilot.

After talking to the pilot, locate Serpo (end of the next trail) back outside the old fort at the second parapet to end this chapter.